A man is in custody after he allegedly threatened flight attendants, passengers and U.S. Air Marshals on a plane that was heading from Philadelphia to London, forcing the plane to turn around.

Unruly Passenger Causes Flight From Philly to Turn Around

Air Marshals escorted the passenger, who according to police was drunk and unruly, off the London-bound plane when it returned to Philadelphia International Airport. (Published Wednesday, May 14, 2014)

"Flight 728 from Philadelphia to London Heathrow returned to Philadelphia because of a disruptive passenger," US Airways spokeswoman Michelle Mohr said.

Investigators identified that passenger as Robert Coppack, who officials say has dual citizenship in the United States and the United Kingdom.

According to officials, two female passengers told flight attendants that Coppack had touched them inappropriately and that they felt uncomfortable sitting next to him. The women claimed that Coppack told them he was drinking vodka and that he appeared to be intoxicated.

After the flight attendants told Coppack not to touch anyone, he allegedly became aggressive, hurling vulgar language at the attendants as well as the passengers around him.

The flight attendants then repeatedly told Coppack to stand up and walk to the back of the aircraft, according to officials. As Coppack walked to the back, he allegedly touched another female passenger, who happened to be a retired flight attendant, on the arm and breast. The passenger claimed Coppack did this on purpose and that the touch was “sexual in nature.”

Officials say Federal Air Marshals who were on the flight then confronted Coppack and told him to behave properly. Coppack allegedly became verbally aggressive and threatened to assault the Marshals if they didn’t leave him alone.

The Marshals then placed Coppack in handcuffs, patted him down and restrained him in a seat in the back of the aircraft, according to an affidavit.

Airport police say the pilots then turned around the Airbus A330-300 jet. The plane landed back in Philly around 1 a.m. and Coppack was removed from the aircraft by several law enforcement officers, a moment captured by passenger Kevin Weissman on Twitter.

Coppack was moved to a detention area with the Federal Inspection Area for an interview. Law enforcement officials also interviewed the flight crew and several passengers about the alleged disturbance.

During his interview, Coppack was allegedly physically aggressive, belligerent and requested to speak to the Consulate of the United Kingdom.

As Coppack remained in custody, the all clear was given for the plane which took off again around 2 a.m. The plane landed in London just after 10 a.m. EST -- the normally 6 ½ hour flight wound up taking more than 11 ½ hours.

Officials say Coppack will be detained in Federal Court in Center City until his scheduled preliminary hearing on Monday. They also say he will be charged with intimidating and interfering with a flight crew.

Coppack's mother told NBC10 her son left California on Tuesday to live in London.

"Obviously my husband and I are shocked and disappointed that Robert would do this," she wrote in an email. "We feel terrible for the other passengers affected by his actions."